Past studies have identified a spatially extended excess of ∼1–3 GeV gamma rays from the region surrounding the Galactic Center, consistent with the emission expected from annihilating dark matter. ...We revisit and scrutinize this signal with the intention of further constraining its characteristics and origin. By applying cuts to the Fermi event parameter CTBCORE, we suppress the tails of the point spread function and generate high resolution gamma-ray maps, enabling us to more easily separate the various gamma-ray components. Within these maps, we find the GeV excess to be robust and highly statistically significant, with a spectrum, angular distribution, and overall normalization that is in good agreement with that predicted by simple annihilating dark matter models. For example, the signal is very well fit by a 36–51 GeV dark matter particle annihilating to bb̄ with an annihilation cross section of σv=(1−3)×10−26cm3/s (normalized to a local dark matter density of 0.4GeV/cm3). Furthermore, we confirm that the angular distribution of the excess is approximately spherically symmetric and centered around the dynamical center of the Milky Way (within ∼0.05∘ of Sgr A∗), showing no sign of elongation along the Galactic Plane. The signal is observed to extend to at least ≃10∘ from the Galactic Center, which together with its other morphological traits disfavors the possibility that this emission originates from previously known or modeled pulsar populations.
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We present MadDM v.3.0, a numerical tool to compute particle dark matter observables in generic new physics models. The new version features a comprehensive and automated framework for dark matter ...searches at the interface of collider physics, astrophysics and cosmology and is deployed as a plugin of the MadGraph5_aMC@NLO platform, inheriting most of its features. With respect to the previous version, MadDM v.3.0 can now provide predictions for indirect dark matter signatures in astrophysical environments, such as the annihilation cross section at present time and the energy spectra of prompt photons, cosmic rays and neutrinos resulting from dark matter annihilation. MadDM indirect detection features support both 2→2 and 2→n dark matter annihilation processes. In addition, the ability to compare theoretical predictions with experimental constraints is extended by including the Fermi-LAT likelihood for gamma-ray constraints from dwarf spheroidal galaxies and by providing an interface with the nested sampling algorithm PyMultiNest to perform high dimensional parameter scans efficiently. We validate the code for a wide set of dark matter models by comparing the results from MadDM v.3.0 to existing tools and results in the literature.
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Radiation-tolerant dose sensor based on undoped amorphous silicon Saha, Anwesha; Guo, L. Jay; Hammig, Mark D.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
September 2024, 2024-09-00, Volume:
1066
Journal Article
Peer reviewed
Single-crystal silicon diodes are replacing gas-filled dose-rate meters because they are batch-processable, mechanically robust, compact, and operable at low voltages. However, they are prone to ...radiation damage in high dose fields. Hydrogenated amorphous silicon (a-Si:H) provides the manufacturing and operational benefits of silicon while adding inherent radiation hardness because of its wider bandgap and disordered microstructure. Previously, sensors with tens of micrometers thick a-Si have been investigated for direct dose sensing in x-ray imaging applications. However, the limited charge carrier lifetimes of the medium can reduce the charge collection efficiency and thereby the sensitivity. If a higher density, higher Z active media is coupled to thin amorphous silicon active layers, then an additional indirect component can be added to this direct signal to exhibit ∼15 μGy/s dose-rate sensitivities at zero and low-bias (<0.5 V) operation. Here we show that thin (150, 300, 450 nm) a-Si:H optical sensors can produce external quantum efficiencies above 40% and internal quantum efficiencies that exceed 70 % over a broad band from 380 nm to 650 nm, resulting in dose-rate sensitivity even at 0 V. When the charge-collecting electrodes abutting the a-Si:H serve the dual purpose as reflective layers in a lossy Fabry-Perot cavity, then internal quantum efficiencies greater than 83 % can be realized in a 30 nm thick layer at 410 nm. Cobalt-60 gamma-ray irradiation to 100 kGy (air) shows no radiation-induced degradation for even the thicker 300 nm sample; rather, a radiation hardening effect is observed as evinced in reduced dark current.
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micrOMEGAs is a code to compute dark matter observables in generic extensions of the standard model. This version of micrOMEGAs includes a generalization of the Boltzmann equations to take into ...account the possibility of two dark matter candidates. The modification of the relic density calculation to include interactions between the two dark matter sectors as well as semi-annihilation is presented. Both dark matter signals in direct and indirect detection are computed as well. An extension of the standard model with two scalar doublets and a singlet is used as an example.
Program title: MicrOMEGAs4.1
Catalogue identifier: ADQR_v4_0
Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADQR_v4_0.html
Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland
Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html
No. of lines in distributed program, including test data, etc.: 738425
No. of bytes in distributed program, including test data, etc.: 9807620
Distribution format: tar.gz
Programming language: C and Fortran.
Computer: PC, Mac.
Operating system: UNIX (Linux, Darwin).
RAM: 50MB depending on the number of processes required.
Classification: 1.9, 11.6.
Catalogue identifier of previous version: ADQR_v3.0
Journal reference of previous version: Comput. Phys. Comm. 185 (2014) 960
External routines: CalcHEP, SuSpect, NMSSMTools, CPSuperH, LoopTools, HiggsBounds
Does the new version supersede the previous version?: Yes
Nature of problem: Calculation of the relic density and direct and indirect detection rates of the lightest stable particle in particle physics models with at most two stable dark matter candidates.
Solution method: In the case where the two dark matter particles have very different masses, we find that the equations for the evolution of the density of dark matter behave as stiff equations. To solve these we use the backward scheme and the Rosenbrock algorithm. The standard solution based on the Runge–Kutta method is still used for models with only one dark matter candidate.
Reasons for new version: There are many experiments that are currently searching for the remnants of dark matter annihilation and the relic density is determined precisely from cosmological measurements. In this version we generalize the Boltzmann equations to take into account the possibility of two dark matter candidates. Thus, in solving for the relic density we include interactions between the two dark matter sectors as well as semi-annihilation. The dark matter signals in direct and indirect detection are computed as well.
Summary of revisions:•Generalization of the Boltzmann equations to include two dark matter candidates, their interactions and semi-annihilations, the relative density of the two dark matter components is taken into account when computing direct/indirect detection rates.•Upgrade of the numerical method for solving the Boltzmann equations.•Include sample extensions of the standard model with extra doublet and singlets which contain two stable neutral particles.Unusual features: Depending on the parameters of the model, the program generates additional new code, compiles it and loads it dynamically.
Running time: 4 sec
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micrOMEGAs is a code to compute dark matter observables in generic extensions of the standard model. This new version of micrOMEGAs is a major update which includes a generalization of the ...Boltzmann equations to accommodate models with asymmetric dark matter or with semi-annihilation and a first approach to a generalization of the thermodynamics of the Universe in the relic density computation. Furthermore a switch to include virtual vector bosons in the final states in the annihilation cross sections or relic density computations is added. Effective operators to describe loop-induced couplings of Higgses to two-photons or two-gluons are introduced and reduced couplings of the Higgs are provided allowing for a direct comparison with recent LHC results. A module that computes the signature of DM captured in celestial bodies in neutrino telescopes is also provided. Moreover the direct detection module has been improved as concerns the implementation of the strange “content” of the nucleon. New extensions of the standard model are included in the distribution.
Title of program: micrOMEGAs3.
Program obtainable from:http://lapth.cnrs.fr/micromegas
Computers for which the program is designed and others on which it has been tested: PC, Mac
Operating systems under which the program has been tested : UNIX (Linux, Darwin)
Programming language used: C and Fortran
Memory required to execute with typical data: 50 MB depending on the number of processes required.
No. of processors used: 1
Has the code been vectorized or parallelized: no
No. of bytes in distributed program, including test data: 70736 kB
External routines/libraries used: no
CPC Program Library subprograms used: CalcHEP, SuSpect, NMSSMTools, CPSuperH, LoopTools, HiggsBounds
Catalogue identifier of previous version: ADQR_v1_3
Journal reference of previous version: Comput. Phys. Comm. 182 (2011) 842
Does the new version supersede the previous version: yes
Nature of physical problem: Calculation of the relic density and direct and indirect detection rates of the lightest stable particle in a generic new model of particle physics.
Method of solution: In numerically solving the evolution equation for the density of dark matter, relativistic formulae for the thermal average are used. All tree-level processes for annihilation and coannihilation of new particles in the model are included as well as some 3-body final states. The cross-sections for all processes are calculated exactly with CalcHEP after definition of a model file. The propagation of the charged cosmic rays is solved within a semi-analytical two-zone model.
Reasons for the new version: There are many experiments that are currently searching for the remnants of dark matter annihilation and the relic density is determined precisely from cosmological measurements. In this version we add the computation of dark matter signals in neutrino telescopes, we generalize the Boltzmann equations so as to take into account a larger class of dark matter models and improve the precision in the prediction of the relic density for DM masses that are below the W mass. We compute the signal strength for Higgs production in different channels to compare with the results of the LHC.
Summary of revisions:•Generalization of the Boltzmann equations to include asymmetric dark matter and semi-annihilations: the DM asymmetry is taken into account when computing direct/indirect detection rates.•Incorporating loop-induced decays of Higgs particles to two-photons and two-gluons, and computing the signal strength for Higgs production in various channels that can be compared to results from LHC searches.•New module for neutrino signature from DM capture in the Sun and the Earth•Annihilation cross sections for some selected 3-body processes in addition to the 2-body tree-level processes. The 3-body option can be included in the computation of the relic density and/or for annihilation of dark matter in the galaxy.•Possibility of using different tables for the effective degrees of freedom in the early Universe•Annihilation cross sections for the loop induced processes γγ and γZ0 in the NMSSM and the CPVMSSM•New function for incorporating DM clumps•New function to define the strange quark content of the nucleon•The LanHEP source code for new models is included•New models with scalar DM are included (Inert doublet model and model with Z3 symmetry)•New implementation of the NMSSM which uses the Higgs self-couplings and the particle spectrum calculated in NMSSMTools_4.1•New versions of spectrum generators used in the MSSM (Suspect_2.4.1) and in the CPVMSSM (CPsuperH2.3)•Extended routines for flavor physics in the MSSM•New facilities to compute DM observables independently of the model•Update in interface tools to read files produced by other codes, this allows easy interface to other codesTypical running time: 4 s
Unusual features of the program: Depending on the parameters of the model, the program generates additional new code, compiles it and loads it dynamically.
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Neutrino detectors participate in the indirect search for the fundamental constituents of dark matter (DM) in form of weakly interacting massive particles (WIMPs). In WIMP scenarios, candidate DM ...particles can pair-annihilate into Standard Model products, yielding considerable fluxes of high-energy neutrinos. A detector like ANTARES, located in the Northern Hemisphere, is able to perform a complementary search looking towards the Galactic Centre, where a high density of dark matter is thought to accumulate. Both this directional information and the spectral features of annihilating DM pairs are entered into an unbinned likelihood method to scan the data set in search for DM-like signals in ANTARES data. Results obtained upon unblinding 3170 days of data reconstructed with updated methods are presented, which provides a larger, and more accurate, data set than a previously published result using 2101 days. A non-observation of dark matter is converted into limits on the velocity-averaged cross section for WIMP pair annihilation.
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We present the third release of the CLUMPY code for calculating γ-ray and ν signals from annihilations or decays in dark matter structures. This version includes the mean extragalactic signal with ...several pre-defined options and keywords related to cosmological parameters, mass functions for the dark matter structures, and γ-ray absorption up to high redshift. For more flexibility and consistency, dark matter halo masses and concentrations are now defined with respect to a user-defined overdensity Δ. We have also made changes for the user’s benefit: distribution and versioning of the code via git, less dependencies and a simplified installation, better handling of options in run command lines, consistent naming of parameters, and a new Sphinx documentation at http://lpsc.in2p3.fr/clumpy/.
Program Title:CLUMPY
Program Files doi:http://dx.doi.org/10.17632/4n33mbh9bc.1
Licensing provisions: GPLv2
Programming language: C/C++
External routines/libraries:GSL (http://www.gnu.org/software/gsl), cfitsio ( http://heasarc.gsfc.nasa.gov/fitsio/fitsio.html), CERN ROOT (http://root.cern.ch; optional, for interactive figures and stochastic simulation of halo substructures), GreAT (http://lpsc.in2p3.fr/great; optional, for MCMC Jeans analyses)
Nature of problem: Calculation of the γ-ray and ν signals from dark matter annihilation/decay at any redshift z.
Solution method: New in this release: Numerical integration of moments (in redshift and mass) of the mass function, absorption, and intensity multiplier (related to the DM density along the line of sight).
Restrictions: Secondary radiation from dark matter leptons, which depends on astrophysical ingredients (radiation fields in the Universe) is the last missing piece to provide a full description of the expected signal.
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The indirect detection of dark matter annihilation and decay using observations of photons, charged cosmic rays and neutrinos offers a promising means of identifying the particle nature of this ...elusive component of the universe. The last decade has seen substantial advances in observational data-sets, complemented by new insights from numerical simulations, which together have enabled for the first time strong constraints on dark matter particle models, and have revealed several intriguing hints of possible signals. This review provides an introduction to indirect detection methods and an overview of recent results in the field.
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Dark matter interactions with electrons or protons during the early Universe leave imprints on the cosmic microwave background and the matter power spectrum, and can be probed through cosmological ...and astrophysical observations. These interactions lead to momentum and heat exchange between the ordinary and dark matter components, which in turn results in a transfer of pressure from the ordinary to the dark matter. We explore these interactions using a diverse suite of data: cosmic microwave background anisotropies, baryon acoustic oscillations, the Lyman-α forest, and the abundance of Milky-Way subhalos. We derive constraints using model-independent parameterizations of the dark matter–electron and dark matter–proton interaction cross sections and map these constraints onto concrete dark matter models. Our constraints are complementary to other probes of dark matter interactions with ordinary matter, such as direct detection, big bang nucleosynthesis, various astrophysical systems, and accelerator-based experiments. They exclude sufficiently large cross sections for a large range of dark matter masses, which cannot be accessed by direct-detection experiments due to the overburden from the Earth’s atmosphere or crust. ▪
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